Manufacture of sand cores



April 13, 1948. R. DAINTY MANUFACTURE OF SAND CORES Filed March 25, 19443 Sheets-Sheet l April 13,1948. R. D AINTY 2,439,563

MANUFACTURE OF sAub conss Filed Max ch 23, 1944 3 Sheets-Sheet 2mil/(May FIG.3'

April 13, 1948. DNNTY f 2,439,563

MANUFACTURE OF SAND corms Filed March 23, 1944 r 3 Sheets-Sheet 5 -7 1-/NVENTOR' 204.4%; izflajifiia Patented Apr. 13, 1948 UNITED STATEMANUFACTURE OF SAND CORES Ralph Dainty, Willenhall, England- ApplicationMarch 23, 1944, Serial No. 527,714

In Great Britain January 15, 1943 Section 1, Public Law 690, August 8,1946 Patent expires February 14, 1964 This invention relates toimprovements in making cores for castings and refers particularly to themaking of cores of substantial length and of uniform cross-section, asfor example cylindrical cores for use in casting bearing bushes or thelike or cores of square or other polygonal cross-sections.

Such cores are commonly made by hand ramming the prepared sand into ahollow. cylindrical former and this is a slow and laborious operationand depends to a certain extent on the skill of the operator for theuniformity and surface finish of the core.

The object of our invention is to provide means whereby cores of a highdegree of accuracy canbe produced rapidly and with a minimum of labour.

According to our invention an number of bores of the required shape forthe cores are formed in a stationary block or the like and sand fed intothe bores is rammed by a corresponding number of rammers or plungersyieldingly mounted on a frame or carrier which is adapted to bereciprocated by manual or other means.

During the core-making operation the lower ends of the bores in theblock may be closed by a plate in contact with the lower face of theblock or they may be closed by means such as pegs which are verticallyadjustable to vary theeifective length of the bores and hence of thefinished cores. The pegs may be moved upwardly at the end of the rammingoperation to eject the finished cores from the upper ends of the boresin the block or the plate or the pegs may be withdrawn to allow thefinished cores to be ejected from the lower ends of the bores by theramming plungers.

In making the cores the operator has a supply of prepared sand adjacentthe block in which the cores are formed and brings the sand over theblock to fill the bores. The frame carrying the rammers is then broughtdown to ram this sand in each bore simultaneously, the frame is'releasedmore sand is brought over the block to fill up the bore again the frameis brought down and so on until the bores are filled and tightly rammed.A scraper is then traversed over the surface of the block to clear offsurplus sand and smooth off the top ends of the cores and the finishedcores are ejected out of the bores ready for drying. Only a small numberof operations is required to make the cores and the operatorsimultaneously makes a number of cores corresponding to the number ofbores in the block.

The yielding mounting of the rammers in the frame ensures that an equalpressure is applied to the sand in each bore irrespective of whether 1Claim. (01. 22-10) the bores are equally filled and also ensures thatthe ramming is effected by a combined impact and squeezing actioninstead. of by an impact action only. This produces uniform and closelycompacted cores.

Thera-mming plungers may be yieldlngly loaded by springs, or thespring-loaded plungers may be replaced by pistons working in air-tightcylinders or by any other means which will allow the plungers to moveaxially against resilient resistance as the sand in the bores iscompressed so that the ramming is effected by a combined impact andsqueezing action.

Two practical forms of core-making machine in accordance with ourinvention are illustrated by way of example in the accompanying drawingsin which- Figure 1 is a side elevation of one form of the machine.

Figure 2 is a side elevation of an alternative form of machine.

Figure 3 is a plan of the machine shown in Figure 2.

Figure 4 is a plan of the upper part of the plunger assembly showing'onemeans for'locking the plunger.

In the machine shown in Figure 1, i0 is a steel block in which areformed a number of parallel vertical bores I l of a cross-sectioncorresponding to that of the cores to be made, the bores extendingthrough the block. The bores are preferably slightly tapered tofacilitate the ejection of the finished cores.

The block is rigidly mounted in an opening in a bench l2 by means offrame-bars l3.

A pair of parallel arms 14 of angle or other .rigid section and ofsubstantial length are pivotally mounted at It; on the rear ends of theframe bars l3, and at their forward ends they carry a frame consistingof a pair of parallel plates l6 rigidly connected by spacing studs l1.Slldably mounted in the frame are a series of parallel plungers [8corresponding in number and spacing to the bores in the block abovewhich the frame normally lies. The cross-sectional dimensions of eachplunger are less than that of the bore with which it co-operates and onthe lower end of the plunger is fixed a head I9 whichserves for theactual ramming of the sand, the plunger projecting below the frame for adistance equal to or slightly more than the length of thebores. vAcoiled compression spring 20 is mounted on each plunger between theplates of the frame and abuts between the upper plate and a shoulder or.collar on the plunger which is urged by the spring against the lowerplate and forms a stop limiting the downward movement of the plungerrelative to the frame.

The lower face of the head IS on the plunger may be serrated or formedwith radial grooves and ribs so that in ramming the sand in the boresthe upper surface of the sand is correspondingly broken up and there iseffective mating and cohesion between successive layers of sand. A

"transverse bar 22 between the arms l4 in front of their pivot isconnected by a substantially vertical link 23 passing through the benchto a lever 24 pivoted at its rear end to a fixed point below the benchand provided with a pedal 25 at its for.. ward end. Thus by depressingthe pedal with the foot the operator swings the arms and the frame downto force the plungers into the bores in the block. The return movementis effected by springs 26 which normally hold the arms and frame in theraised position.

During the ramming of the cores the lower ends of the bores in the blockare closed by pegs 21 extending upwardly from a plate 28 slidably guidedon studs 29 extending downwardly from the block. The plate is verticallymovable by a lever 30 which has a pivotal and sliding engagement with astud 3| 'in a fitting 32 secured to the bottom of the table. When theramming of the cores is completed the lever 30 is lifted to raise theplate 28 so that the pegs 21 are forced upwardly into the bores in theblock I and eject the cores which are then taken away for drying.

In the alternative form of the machine shown in Figures 2 to 4 theplunger assembly is guided to move vertically in a. straight line. Y

A block 40 in which are formed a number of parallel vertical bores ismounted in the front part of a cast base 4i adapted to be secured on abench 42. Rigidly mounted in sockets 43 in the base are spaced verticalpillars 44 of cylindrical cross-section on which a carriage 45 is guidedfor vertical movement. Each guide is formed by three pairs of rollers 46engaging the surface of the rod in planes angularly spaced at 120 apart,the rollers of each pair being spaced apart at a substantial distance inan axial direction. Each roller is preferably mounted on an eccentricspindle in a bracket 41 secured to the carriage so that the rollers canbe adjusted very accurately to roll freely on the rods withoutappreciable play. Rigidly mounted in the carriage is a frame formed byvertically spaced plates 48 in which are slidably mounted verticalplungers 49 corresponding in number and spacing to the bores in theblock 40. Each plunger 4 pedal lever 55 but this is not always desirableas if the frame carries a large number of plungers then although theresistance to the movement of each individual plunger may be relativelysmall a considerable force is required to compress the springs of allthe plungers simultaneously in ramming the-cores. This pressure can beobtained by using a high leverage between the pedal lever and thecarriage but this entails a long movement of the pedal. To avoid thisthe pedal lever is preferably arranged to actuatethe carriage throughmechanism giving a rapid movement of the carriage from the rest positionuntil the plungers are just entering the bores in the block and then aslowmovement with a considerably higher leverage. One such mechanism isshown in Figure 2 when the lower end of the strap 54 is connected by aninclined link 58 to the pedal lever and carries a grooved roller 59co-operating with a fixed cam surface 60 of such a form that during thefirst part of the downward movement of the pedal there is a relativelyrapid downward movement of the carriage to bring the plungers down tothe block and then on the later part of the pedal movement there is aslower and more powerful movement of the carriage to urge the plungersinto the bores in the block as there is a step up in projects below theframe for a distance equal to or slightly greater than the length of thebores in the block and is urged downwardly by a compression spring 50mounted on the plunger and abutting between the upper plate of the frameand a collar on the plunger adapted to engage the lower plate.

A lug, 5| on the carriage 45 is coupled by a rod 52 passing through thebench to a bracket 53 on the upper end of a strap 54 which is pivotallyconnected to apedal lever 55. The

carriage with the plunger frame is normally held in the raised positionshown in Figure 2 by tension springs 56 connected between the bracket 53and anchorages 51 on the bottom of thebench, andris-brought down toforce the plungers into the bores in the block by depressing the pedallever 55.

The strap 54 may be connected directly to the the leveragebetween thepedal and the strap 54,

If cores of the full length of the bores in the block are required thebottom ends of the cores may be. closed during the ramming operation bya plate sliding into guides in the base casting so that the plate isheld against the bottom of the block.

After the cores have been rammed the plate is slid out of these guidesand into others at a lower level so that the plate is then spaced fromthe bottom of the block by a distance greater than the length of thebores and by bringing the plungers down again the rammed cores areejected downwardly from the bores and left standing vertically on theplate ready for taking away to be dried.

In the arrangement illustrated the lower ends of the bores are closedduring the ramming of the cores by pegs 6| extending upwardly from aplate 62 mounted on the upper ends of rods 63 passing through the benchand through a plate 64 secured to the bottom of the bench. The lowerends of these rods are secured to a bar 65 through which passes ascrewed sleeve 66 fitting over a spindle 61 which is secured at itslower end to a lever 68 and-is guided at its upper end in the plate 64.The bar 65 is supported by a nut 69 adjustably screwed on to the sleeve66.

The lever 68 is pivoted at its inner end by a link 10 to a lug H on thebottom of the bench and adjacent its outer end carries a catch 12adapted to engage with a lug 13 on the front of the bench.

'Before the cores are rammed the lever is raised until the catch 12engages with the lug 13. This raises the bar 65 and with it the plate 52so that the pegs 6| enter and close the. lower ends of the bores in theblock 40, the pegs being rigidly supported by the lever 68.

The extent to which the pegs 6| enter the bores and hence the length ofthe cores is ad-' ends of the bores, a plate or equivalent meanspreferably being slid on to the bench under the block to receive them.

In ejecting the rammed cores by means of the resiliently-loaded plungersthere is a possibility that a core may stick in the'bore until theplunger spring has been compressed for some distance so that the core isejected with considerable force and speed and may be damaged. To avoidthis means may be provided for lockingtheplungers rigidly againstmovement in the frame during the ejecting of the cores.

One such means is shown in Figure 4. It comprises a plate 14 having'anumber of openings corresponding in number and spacing to the plungerswhich overlies the upper plate of the plunger frame and has a limitedsliding movement thereon by means of slots 15in the plate co-operatingwith the studs 16 and nuts 11 which secure the plates of the frametogether. In one position of the plate 14 the openings in this plateregister with the upper ends of the plungers which can move freelythrough the plate while in another position the openings are out ofregister with the plungers which are then looked against movementrelative to the frame and move as a rigid unit with the frame.

While the apparatus has been described above as having the bores in theblock vertical and the frame carrying the plungers moving in a verticaldirection it will be obvious that for some purposes it may i bedesirable to arrange the bores in the block horizontally. in which casethe frame will move in a horizontal direction.

The solid block having bores in which the cores are formed and fromwhich they are ejected in an axial direction may be replaced by a splitcore stock divided in a plane containing the axes of a number of alignedmoulds, the two parts of the stock being clamped together while thecores are being rammed and being separated subsequently to allow thecores to beulift'ed out or A turned out on to a grooved plate orcore-rest.

Several of such split stocks may be clamped together by quick-actingclamps or the like to form a block which is located in the machine bydowels or other suitable locating means.

Further, while the apparatus has been designed primarily formaking sandcores it can be used for any other purpose where pulverulent materialsuch as core sand or earth has to be compacted into a cylindrical orsimilar form.

I claim: a

Apparatus for the simultaneous manufacture of a plurality of rod-likesand cores or the like comprising a plurality of parallel stationarymoulds, movable means for closing the moulds at one end during theformation of the cores, a frame guided to move in a path substantiallyparallel to the axes of the moulds, means for moving the frame towardsand away from the moulds, a plurality of plungers corresponding innumber and spacing to the moulds yieldingly mounted in and projectingfrom the frame and adapted to enter and yieldingly ram sand in themoulds, said frame including two spaced plates, one of 'said platesbeing provided with openings in which said plungers are guided, theother plate being provided with similarly arranged openings and beingshiftable in its plane, so that the plungers can move freely throughsaid other plate when the openings of both plates register, but

are locked when the openings are out of registry.

RALPH DAINTY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Augustine Jan. 8, 1907 Schwarzkopf Apr. 16, 1907Ford Sept. 16, 1913 Graves May 27, 1919 Smith June 16, 1925 Elton et al.Dec. 3, 1929 Sebring Oct. 23, 1934 Hammer Oct. 10, 1893

